Default route (IPv4) demolished by destroying clone (gif/gre) interface

[Brooks Davis]

On Wed, Aug 16, 2006 at 07:58:44PM +0400, Yar Tikhiy wrote:
> On Wed, Aug 16, 2006 at 09:54:19AM -0500, Brooks Davis wrote:
> > On Wed, Aug 16, 2006 at 10:23:13AM +0200, Stefan Bethke wrote:
> > > 
> > > Ouch. Don't ppp(8), OpenVPN etc. destroy the tun interface they're  
> > > using when they exit?  Flushing all routes then would be rather  
> > > harmful.  I'm glad I haven't updated to a newer -stable yet then :-)
> > 
> > In general, no since tun interfaces can not be destroyed.
> 
> Did you mean "in particular"? :-)
> 
> The problem can be triggered by destroying any interface that can
> be destroyed.  Just imagine getting rid of a defunct gif tunnel on
> a remote router, or removing an unused vlan, and totally losing
> connectivity to the router due to its default route having been
> flushed.  The scenario still can be quite unpleasant.  I'd rather
> change the default for $removable_route_flush to NO and let the
> kernel choose which routes should be flushed upon the physical
> ejection or software destruction of an interface.  Note that this
> doesn't include static_routes_${ifn}, which are handled separately
> by pccard_ether_stop().

Agreed.  That code shouldn't be on by default.  I've disabled in it HEAD
and will MFC in a few days.  As another poster said, I'm not even sure
it should exist as an option.

-- Brooks
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